Covalently attached carbohydrates are recognized as informational components of glycoproteins, and are known to influence the kinetics and sites of catabolism of circulating glycoproteins. In our basic, biomedical research, we are studying three aspects of the function of carbohydrate in plasma protein catabolism: (1) the role of the mannose recognition system in reticuloendothelial tissues in the clearance of antigen-antibody complexes from the circulation, (2) the influence of complex sialyl-terminal carbohydrates on sites of catabolism of plasma glycoproteins, and (3) the effects of nonezymatic glucosylation of plasma proteins on their chemical, physical and biological properties and rates of catabolism in vivo. In more directly health-related studies, we are also evaluating: (1) the hypothesis that the virulence of various strains of Candida albicans is affected by the nature of the interaction of yeast cell-surface mannans with the mannose recognition system in vivo; and (2) the role of non-enzymatic glucosylation of protein in the pathophysiology of diabetes. In clinical studies we are collaborating with physicians to evaluate the usefulness of measurements of serum protein glucosylation for the detection of glucose intolerance and the diagnosis and management of diabetes. The long-term objective of this research is to elucidate the function of carbohydrate-specific recognition systems and non-enzymatic glycosylation of protein in physiological and pathological processes in man.